北运河流域(北京段)沉积物中PAHs污染特征与风险评估

Pollutant Characteristics and Risk Assessment of Polycyclic Aromatic Hydrocarbons in the Sediment of the North Canal Basin(Beijing Section)

为探明北运河流域(北京段)多层沉积物中PAHs(多环芳烃)的污染状况,利用活塞式底泥取样器于2014年11月采集了9处沉积物样品,取样深度为30~80 cm,每处样品根据其垂向介质特征大致分成3~4层,分别测定各层样品的粒径、TOM(总有机质)及16种PAHs的质量分数,探讨PAHs在河道沿程与垂向上的分布特征、来源及生态风险评价.结果表明,北运河流域(北京段)沉积物以砂质壤土为主,w(TOM)(以干质量计,下同)为103.4~146.8 g kg,w(∑16 PAHs)为598.1~28730.6 ng g,各层w(∑16 PAHs)为108.5~8810.8 ng g.沉积物中PAHs以高环为主,主要包括有Phe(Phenanthrene,菲)、Fla(Fluoranthene,荧蒽)、Pyr(Pyrene,芘)、BbF〔Benzo(b)fluoranthene,苯并[b]荧蒽〕.在河道沿程变化上,中下游沉积物的污染程度远高于上游.在垂向变化上,w(TOM)和沉积物粒径对PAHs的分布影响有限,PAHs的垂向分布主要受所处沉积环境与历史污染程度影响.根据主成分分析与同分异构体比值法推断,PAHs主要来源于化石燃料与生物燃料的燃烧,少部分为石油源.利用效应区间值得出的生态风险评价结果表明,北运河流域(北京段)沉积物中PAHs可能已对环境产生负面影响,其中BbF、BkF、InP与BgP已对环境产生毒副作用,需要给予关注与解决.

To explore the pollution of polycyclic aromatic hydrocarbons(PAHs)in the multi-layer sediments of the North Canal Basin(Beijing section),9 sediment samples were collected by a piston-type mud sampler in November 2014.The sampling depth ranges from 30 to 80 cm.Each sample was roughly divided into 3-4 layers according to its vertical soil characteristics.The particle size,total organic matter(TOM)and the content of 16 PAHs in the multilayer sediments were analyzed.Moreover the characteristics,sources and ecological risk assessment of PAHs were discussed.The results showed that the multi-layered sediments were mainly sandy loam,w(TOM)ranged from 103.4 to 146.8 g kg,w(∑16 PAHs)ranged from 598.1 to 28,730.6 ng g,and the w(∑16 PAHs)in each layer changed between 108.5 and 8,810.8 ng g.Most of the PAHs in the sediments were high-ring PAHs such as Phenanthrene,Fluoranthene,Pyrene and Benzo(b)fluoranthene.Downstream sediments were much more polluted than upstream.The influence of TOM and particle size on the distribution of PAHs was limited.The vertical distribution of PAHs was mainly affected by the sedimentary environment and historical pollution degree.Principal component analysis and isomer ratio method were used to determine the sources of PAHs.It showed that PAHs were mainly derived from the combustion of fossil fuels and biofuels,and a small part of them was originated from petroleum.Furthermore,the results of effect range method demonstrated that PAHs in the sediments of the North Canal Basin(Beijing section)may have a negative impact on the environment.BbF,BkF,InP and BgP have toxic side effects on the environment.Therefore some measures should be taken to deal with the PAHs pollution problem in the North Canal Basin(Beijing section).